Thermostat control systems typically include a thermostat unit for sensing climate conditions (e.g., temperature) and controlling an associated Heating Ventilating and Air Conditioning (HVAC) system. Multiple thermostat units may be provided with each controlling a separate climate zone using a single HVAC system or separate HVAC systems. For example, a separate thermostat unit may be provided on each floor of a home for separately controlling (i.e., monitoring and activating) the heating and cooling on each floor (usually, but not necessarily) using separate heating and air conditioning units.
Even with multiple thermostat units or separate climate zones, maintaining a comfortable temperature level in different portions of a building during different times of day is very difficult. A programmable thermostat unit may be used to provide additional climate control (e.g., different set point temperatures during different time periods). However, it is still difficult to achieve comfortable climate levels in different rooms throughout the day because of changes in internal home environment conditions that are typically hard to predict and control (e.g., opening and closing blinds in different rooms and/or opening and closing various external doors).
Oftentimes the thermostat unit is installed in a location (e.g., kitchen hallway) that is not desirable for temperature measurements relative to other rooms in a building (e.g., a house). Also, individuals in a house usually occupy different rooms at different times of the day. Thus, the thermostat unit fails to accommodate the climate control needs of occupants at various times of the day. Further, outdoor conditions, including for example, the angle of the sun, may affect internal house temperature in different rooms. This further increases the problem of maintaining comfortable climate levels in different rooms of a house throughout the day.
Attempts to address these problems and maintain better climate control within a building include providing wired and remote temperature sensor devices in rooms separate from the main thermostat unit. These sensors typically provide temperature and other climate information to the thermostat unit for use in controlling an associated HVAC system based upon transmitted climate condition information from the sensors in specific rooms. Thus, depending upon which room of the house is most often used during a particular time period, the thermostat may be programmed to use the transmitted sensed temperature information from the sensor in that particular room to activate cooling and/or heating. The thermostat unit may be configured for processing sensed transmitted climate conditions from more than one remote sensor to thereby control an HVAC system to heat and/or cool a building. Such a thermostat unit is the 1F95-479 model thermostat, manufactured and sold by the White-Rodgers Division of Emerson Electric Co.
Remote sensors are usually more desirable than wired sensors because of the ease of installation (i.e., no hard wiring required). However, remote sensors are typically powered by replaceable internal power supplies (e.g., batteries), making power conservation (i.e., reducing power consumption and usage) a larger concern. Conserving power is also a concern in battery powered thermostat units. For example, if a climate control system is replaced, with the associated thermostat unit also replaced, additional sources of power (e.g., an internal power supply) for the thermostat unit may be required to control the new system, such as when replacing a single stage system with a multi-stage system.
Systems and devices are known that attempt to conserve or save power in order to extend the life of the replaceable power supplies within specific devices of a thermostat control system. Some of these systems transmit only at lower power levels, which may result in a failure to provide reliable transmissions depending upon the distance between the thermostat unit and sensors, as well as other interference. In other known systems, the number of transmissions from a remote sensor may be reduced, for example, by transmitting temperature information only after a predetermined time period. Although this may conserve power, unnecessary transmissions can occur during extended periods in which temperature variations do not exceed a fraction of a degree in temperature. For example, if the temperature in a house remains relatively constant at 70 degrees for a two hour period, a sensor that transmits on a periodic basis would waste power transmitting the same temperature value to the thermostat, which would accordingly hold the heating and cooling systems in an off state.
Still other systems include devices having different types of low-power transmitters, which are typically costly, and again may fail to provide reliable transmissions. With such a system, multiple sensors or transmitting units may be required to transmit sensed temperature information from the remote sensing unit to the main thermostat unit located a distance from the remote sensor (i.e., transmit from one unit to the next).
Therefore, these known systems and devices fail to provide power saving transmissions (i.e., reduction in power consumption) while ensuring reliable and timely sensed climate information. This can result in unacceptable temperature levels. Further, these systems and devices are generally costly to manufacture.